Field of the Invention
The invention relates to the field of electrode materials and electrochemical energy storage, and, in particular, to a novel phosphate based composite anode material, preparation method and use thereof.
Description of Related Art
Due to the problems of traditional energy, such as non-renewability, environmental pollution, there are great concerns for clean energy all over the world. Clean energy, to name a few, currently includes nuclear, solar, wind, hydro and bio-energy. Obtaining clean energy from nature has become an emerging technology, prompting the booming development of clean energy storage technologies.
Therein, the secondary-ion battery (e.g. lithium-ion battery, sodium-ion battery, etc.), especially the lithium-ion battery, attracts great attention due to its characteristics, such as lack of memory, high energy density, long service life, good safety, non-toxicity, low pollution, and becomes the most preferred choice for electric vehicle battery.
The lithium ion battery anode material is the most important component for the battery and the key factor determining the capacity, safety, service life and price of the lithium-ion battery. The currently commonly used anode materials are lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese ternary materials (LiNi1/3Co1/3Mn1/3O2), lithium manganese oxide (LiMn2O4), phosphate (LiFePO4, Li3V2(PO4)3), and so on. Among these materials, lithium cobalt oxide (LiCoO2) is the most researched and the market leader. However, it is expensive, detrimentally effects environment and lithium cobalt oxide has poor safety and, therefore, it can not be used in the field of power batteries. Nickel cobalt manganese lithium ternary materials (LiNi1/3Co1/3Mn1/3O2) are unstable in lattice structure, prone to produce oxygen, and of high cost and poor safety, thereby seriously affecting its practical application. Lithium manganate (LiMn2O4) has low reversible capacity, about 110 mAh/g in practice, and lower volume capacity. The manganese ions in the crystal lattice are prone to dissolve above 55° C., causing structural damage to the crystal, poor cycle stability and life. While lithium iron phosphate (LiFePO4) of the phosphate series has a good cycle stability, safety, and a high reversible capacity, its low voltage platform and low tap density result in a lower volume capacity and weight capacity, and it is difficult to monitor battery capacity due to the flat voltage platform.
Recently, Lithium vanadium phosphate (Li3V2 (PO4)3), which belongs to polyanionic anode material, has attracted great attention due to the high-voltage, high-capacity and high stability characteristic of polyanionic material as well as good cycle performance and a wide range of temperature adaptability. However, the pure phase lithium vanadium phosphate (Li3V2(PO4)3) is expensive, and its 4.6V voltage platform can not be physically applied under the current electrolyte system, resulting in the actual reversible capacity of about 130 mAh/g, therefore it is difficult to use it independently. Moreover, lithium resources of the world are relatively limited and mostly concentrated in South America, therefore, the large-scale use of lithium-ion batteries will inevitably lead to the depletion of such resources.
Consequently, there is an urgent need to develop an anode composite material which is inexpensive and has good electrochemical performance.